In recent years, hydrotherapy vessels have become increasingly popular for both medical and social usage. In the past, the use of hydrotherapy vessels (sometimes known as "Jacuzzis") was generally limited to medical or physical therapy purposes; for example, athletes having muscle strains would commonly be subjected to hydrotherapy to relieve pain and increase circulation, thereby facilitating recovery. In recent years, the use of hydrotherapy vessels for social purposes and relaxation has undergone spectacular growth, particularly in the Western United States. Units may be located outdoors, either in conjunction with a swimming pool, or independently. These units are usually relatively large, holding from 150 to about 800 gallons, and chemicals for modifying water pH and controlling growth of bacteria are added similarly to the treatment of swimming pools.
A new type of hydrotherapy vessel is a bathtub equipped with water circulating mechanisms. These bathtubs are intended for use indoors, and are sufficiently small to justify filling for each use. These bathtubs are generally molded shells having jet nozzles located at various points on the interior of the tub. A circulating pump brings water from a location near the tub bottom and pumps it through the jets, thereby creating desired turbulence. Air intake ports built into the jet permit air to be sucked into the jet in large quantities according to the Bernouilli effect, creating a large volume of fluid flow. In preparing these hydrotherapy tubs, the user first fills the tub to the desired level with water. He then turns the pump on with a switch that is commonly mounted on a wall timer, and then steps into the tub. Ordinarily, the timer shuts the pump off automatically while the user is still in the tub; otherwise the user shuts it off by hand upon leaving the tub.
Problems have been encountered where the therapy tub user is inexperienced and unfamiliar with the operation of the tub, or when the user is forgetful. If the user does not turn the pump off before emptying the tub, extensive damage can occur. As the tub empties, the water level drops below that of some of the water jets, resulting in a stream of water being sprayed with great force outside of the tub. Hotels have experienced substantial damage to wallpaper and other fixtures as a result of the water pump being left on as the tub is emptied. In addition, when the water drains to a level below the pump suction, the pump will run dry and burn out. Similar major damage to the pump will result if the pump is inadvertently turned on when there is no desire or intent to fill the tub with water, such as where a child turns on the switch.
Several efforts have been made to preclude room or pump damage caused by leaving the water pump on as the tub empties. The use of timers having very short cycles is unacceptable because the user must get out of the tub to reset the timer. In most areas, building codes require that the electrical switch be located at a defined minimum distance from the tub. Float-operated level controls, which turn off the pump mechanically, have been unsuccessful because they are somewhat bulky, and because the floats tend to stick and become inoperable in a relatively short period of time because of deposits caused by the alkalinity of the water. In addition, the floats cannot be located in the user portion of the tub, and must be hidden in an enclosed area.
Accordingly, it is an object of the invention to provide a liquid level controlling system for a hydrotherapy tub which will automatically shut the water pump off when the water in the tub reaches a certain level. It is another object of the invention to provide a hydrotherapy tub liquid level control system which is easy to install, inexpensive, and virtually maintenance free. It is a still further object of the invention to provide a liquid level controller which does not change the shape of a hydrotherapy tub, and does not detract from the appearance of the tub. These and other objects of the invention will become apparent through the following detailed description of the invention.